DevTools protocol interception, blocking & modification of requests

content/browser/devtools/devtools_url_request_interceptor.h

Index: content/browser/devtools/devtools_url_request_interceptor.h
diff --git a/content/browser/devtools/devtools_url_request_interceptor.h b/content/browser/devtools/devtools_url_request_interceptor.h
new file mode 100644
index 0000000000000000000000000000000000000000..8aeb4209d4a113c33820ddcdaf7053df8552f20d
--- /dev/null
+++ b/content/browser/devtools/devtools_url_request_interceptor.h
@@ -0,0 +1,198 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_URL_REQUEST_INTERCEPTOR_H_
+#define CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_URL_REQUEST_INTERCEPTOR_H_
+
+#include "base/containers/flat_map.h"
+#include "base/containers/flat_set.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "base/optional.h"
+#include "content/browser/devtools/protocol/network.h"
+#include "content/public/browser/browser_thread.h"
+#include "net/base/net_errors.h"
+#include "net/url_request/url_request_interceptor.h"
+
+namespace content {
+namespace protocol {
+class NetworkHandler;
+}  // namespace
+
+class BrowserContext;
+class DevToolsURLInterceptorRequestJob;
+class WebContents;
+
+// An interceptor that creates DevToolsURLInterceptorRequestJobs for requests
+// from pages where interception has been enabled via
+// Network.enableRequestInterception.
+class DevToolsURLRequestInterceptor : public net::URLRequestInterceptor {
+ public:
+  explicit DevToolsURLRequestInterceptor(BrowserContext* browser_context);
+  ~DevToolsURLRequestInterceptor() override;
+
+  // Must be called on UI thread.
+  static DevToolsURLRequestInterceptor* FromBrowserContext(
+      BrowserContext* context);
+
+  // net::URLRequestInterceptor implementation:
+  net::URLRequestJob* MaybeInterceptRequest(
+      net::URLRequest* request,
+      net::NetworkDelegate* network_delegate) const override;
+
+  net::URLRequestJob* MaybeInterceptRedirect(
+      net::URLRequest* request,
+      net::NetworkDelegate* network_delegate,
+      const GURL& location) const override;
+
+  net::URLRequestJob* MaybeInterceptResponse(
+      net::URLRequest* request,
+      net::NetworkDelegate* network_delegate) const override;
+
+  enum class CommandStatus {
+    OK,
+    UnknownInterceptionId,
+    CommandAlreadyProcessed,
+  };
+
+  using CommandCallback = base::OnceCallback<void(const CommandStatus& status)>;
+
+  struct Modifications {
+    Modifications(base::Optional<net::Error> error_reason,
+                  base::Optional<std::string> raw_response,
+                  protocol::Maybe<std::string> modified_url,
+                  protocol::Maybe<std::string> modified_method,
+                  protocol::Maybe<std::string> modified_post_data,
+                  protocol::Maybe<protocol::Network::Headers> modified_headers);
+    ~Modifications();
+
+    bool RequestShouldContineUnchanged() const;
+
+    // If none of the following are set then the request will be allowed to
+    // continue unchanged.
+    base::Optional<net::Error> error_reason;   // Finish with error.
+    base::Optional<std::string> raw_response;  // Finish with mock response.
+
+    // Optionally modify before sending to network.
+    protocol::Maybe<std::string> modified_url;
+    protocol::Maybe<std::string> modified_method;
+    protocol::Maybe<std::string> modified_post_data;
+    protocol::Maybe<protocol::Network::Headers> modified_headers;
+  };
+
+  struct InterceptedPage {
+    InterceptedPage();
+    explicit InterceptedPage(const InterceptedPage& other);
+    InterceptedPage(WebContents* web_contents,
+                    base::WeakPtr<protocol::NetworkHandler> network_handler);
+    ~InterceptedPage();
+
+    WebContents* web_contents;
+    base::WeakPtr<protocol::NetworkHandler> network_handler;
+  };
+
+  // The State needs to be accessed on both UI and IO threads.
+  class State : public base::RefCountedThreadSafe<State> {
+   public:
+    State();
+
+    // Must be called on the IO thread.
+    void ContinueInterceptedRequest(
+        std::string interception_id,
+        std::unique_ptr<Modifications> modifications,
+        CommandCallback callback);
+
+    // Returns true if |request| should be intercepted and sets
+    // |network_handler|. Must be called on the IO thread.
+    bool ShouldInterceptRequest(const net::URLRequest* request,
+                                const InterceptedPage** intercepted_page) const;

[dgozman, 2017/05/30 21:44:27]

nit: can just return the struct by value, since you allocate one on the stack
anyway. I think this will also eliminate default and copy constructors.

[alex clarke (OOO till 29th), 2017/05/31 15:52:02]

I was able to get rid of the default constructor by using emplace.  Chromium
style candidates the copy constructor however (as enforced by a clang plugin).

[alex clarke (OOO till 29th), 2017/05/31 15:54:37]

Whoops I meant to say Chromium style mandates the copy constructor.

+
+    // Must be called on the IO thread.
+    DevToolsURLInterceptorRequestJob* CreateDevToolsURLInterceptorRequestJob(
+        net::URLRequest* request,
+        net::NetworkDelegate* network_delegate,
+        const InterceptedPage* intercepted_page);
+
+    // Must be called on the UI thread.
+    void StartInterceptingRequests(
+        WebContents* web_contents,
+        base::WeakPtr<protocol::NetworkHandler> network_handler);
+
+    // Must be called on the UI thread.
+    void StopInterceptingRequests(WebContents* web_contents);
+
+    // Registers a |sub_request| that should not be intercepted.
+    void RegisterSubRequest(const net::URLRequest* sub_request);
+
+    // Unregisters a |sub_request|. Must be called on the IO thread.
+    void UnregisterSubRequest(const net::URLRequest* sub_request);
+
+    // To make the user's life easier we make sure requests in a redirect chain
+    // all have the same id. Must be called on the IO thread.
+    void ExpectRequestAfterRedirect(const net::URLRequest* request,
+                                    std::string id);
+
+    // Must be called on the IO thread.
+    void JobFinished(const std::string& interception_id);
+
+   private:
+    class InterceptedWebContentsObserver;
+
+    void StartInterceptingRequestsInternal(
+        int render_frame_id,
+        int frame_tree_node_id,
+        int process_id,
+        WebContents* web_contents,
+        base::WeakPtr<protocol::NetworkHandler> network_handler);
+
+    void StopInterceptingRequestsInternal(int render_frame_id,
+                                          int frame_tree_node_id,
+                                          int process_id);
+    void StopInterceptingRequestsOnIoThread(WebContents* web_contents);
+
+    std::string GetIdForRequest(const net::URLRequest* request,
+                                bool* is_redirect);
+
+    // Returns a WeakPtr to the DevToolsURLInterceptorRequestJob corresponding
+    // to |interception_id|.  Must be called on the IO thread.
+    DevToolsURLInterceptorRequestJob* GetJob(
+        const std::string& interception_id) const;
+
+    base::flat_map<std::pair<int, int>, InterceptedPage>
+        intercepted_render_frames_;
+
+    base::flat_map<int, InterceptedPage> intercepted_frame_tree_nodes_;
+
+    // UI thread only.
+    base::flat_map<WebContents*,
+                   std::unique_ptr<InterceptedWebContentsObserver>>
+        observers_;
+
+    base::flat_map<std::string, DevToolsURLInterceptorRequestJob*>
+        interception_id_to_job_map_;
+
+    base::flat_set<const net::URLRequest*> sub_requests_;
+    base::flat_map<const net::URLRequest*, std::string> expected_redirects_;
+    size_t next_id_;
+
+   private:
+    friend class base::RefCountedThreadSafe<State>;
+    ~State();
+    DISALLOW_COPY_AND_ASSIGN(State);
+  };
+
+  const scoped_refptr<State>& state() const { return state_; }
+
+ private:
+  BrowserContext* const browser_context_;
+
+  scoped_refptr<State> state_;
+
+  DISALLOW_COPY_AND_ASSIGN(DevToolsURLRequestInterceptor);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_URL_REQUEST_INTERCEPTOR_H_